U.S. patent number 10,448,316 [Application Number 16/092,861] was granted by the patent office on 2019-10-15 for method for transmitting system information by a base node.
This patent grant is currently assigned to GEMALTO M2M GMBH. The grantee listed for this patent is Gemalto M2M GmbH. Invention is credited to Volker Breuer, Lars Wehmeier.
United States Patent |
10,448,316 |
Breuer , et al. |
October 15, 2019 |
Method for transmitting system information by a base node
Abstract
A method for transmitting system information by a base node to
at least one wireless communication device camping on the base
node, the base node supporting a dedicated resource region for
communication devices, which is capable of being deployed at least
in-band and out-of-band relative to a common frequency band. The
method includes collecting a configuration parameter for said
dedicated resource region according to a predetermined time period
and to arrange said configuration parameter in system information
blocks. If the dedicated resource region is deployed in-band and a
wideband transmission session is active, adding to at least one of
the system information blocks a valid subframe indication for
submitting system information blocks instead of wideband
transmission blocks, and transmitting said system information
blocks according to said valid subframe indication. In case it is
not deployed in-band, transmitting the system information blocks
unchanged in a carrier frequency outside of the common frequency
band.
Inventors: |
Breuer; Volker (Boetzow,
DE), Wehmeier; Lars (Falkensee, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Gemalto M2M GmbH |
Munich |
N/A |
DE |
|
|
Assignee: |
GEMALTO M2M GMBH (Munich,
DE)
|
Family
ID: |
55913490 |
Appl.
No.: |
16/092,861 |
Filed: |
April 18, 2017 |
PCT
Filed: |
April 18, 2017 |
PCT No.: |
PCT/EP2017/059094 |
371(c)(1),(2),(4) Date: |
October 11, 2018 |
PCT
Pub. No.: |
WO2017/186525 |
PCT
Pub. Date: |
November 02, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190141615 A1 |
May 9, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Apr 29, 2016 [EP] |
|
|
16167799 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
48/12 (20130101); H04W 88/08 (20130101); H04W
84/042 (20130101) |
Current International
Class: |
H04W
4/00 (20180101); H04W 48/12 (20090101); H04W
84/04 (20090101); H04W 88/08 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Gemalto N.V.: "Applicability of Downlink Sub frames for
Transmission", 3GPP Draft, R2-163370, 3rd Generation Partnership
Project (3GPP), May 2016, 2 pages. cited by applicant .
Intel Corporation: "Email discussion report on [NBAH#05] [NBIOT/SI]
System Information", 3GPP Draft, R2-161254
NB-IOT_SI_EMAIL-Discussion-5, 3rd Generation Partnership Project
(3GPP), Feb. 2016, XP051065995, 30 pages. cited by applicant .
International Search Report (PCT/ISA/210) dated Jun. 30, 2017, by
the European Patent Office as the International Searching Authority
for International Application No. PCT/EP2017/059094. cited by
applicant .
RAN WGI: "Status Report to TSG 1 Work plan related evaluation",
3GPP Draft, RP-160183, 3rd Generation Partnership Project (3GPP),
Mar. 2016, XP051076140, 49 pages. cited by applicant .
Samsung: "Impact on System Information for In-band Operations of
NB-IoT", 3GPP Draft, R2-160516 Impact on System Information for
In-Band Operations of NB-IOT, 3rd Generation Partnership Project
(3GPP), Jan. 2016, XP051054802, 2 pages. cited by applicant .
Written Opinion (PCT/ISA/237) dated Jun. 30, 2017, by the European
Patent Office as the International Searching Authority for
International Application No. PCT/EP2017/059094. cited by
applicant.
|
Primary Examiner: Washington; Erika A
Attorney, Agent or Firm: Buchanan Ingersoll & Rooney
PC
Claims
The invention claimed is:
1. Method for transmitting system information by a base node being
part of a cellular wireless network, to at least one wireless
communication device camping on the base node in a frame structure,
the base node being configured to support a dedicated resource
region embedded in the frame structure for a subset of camping
wireless communication devices, wherein the dedicated resource
region is capable of being deployed at least in-band and
out-of-band in relation to a common frequency band, the method
comprising the steps of: collecting configuration parameter for
said dedicated resource region according to a predetermined time
period and to arrange said configuration parameter in system
information blocks, identifying if the dedicated resource region is
deployed in-band, in case it is deployed in-band and a wideband
transmission session is active, adding to at least one of the
system information blocks a valid subframe indication for
submitting system information blocks instead of wideband
transmission blocks, and transmitting said system information
blocks according to said valid subframe indication, in case it is
not deployed in-band transmitting the system information blocks
unchanged in a carrier frequency outside of the common frequency
band.
2. Method according to claim 1, wherein the system information
blocks are transmitted according to a coverage enhancement scheme
comprising a plurality of repetitions, whereby the repetitions are
transmitted in the dedicated resource region in case of in-band
deployment interrupted through at least one of the wideband
transmission blocks and in each subframe otherwise.
3. Method according to claim 2, further comprising the step of
evaluating if the wideband transmission session is active and if
the system information blocks are supposed to be transmitted
according to an coverage enhancement scheme, and deploying at least
one system information block out-of-band in case of the active
wideband transmission session.
4. Method according to claim 3, further comprising the step of
transmitting at least one system information block repeatedly
according to a frequency hopping sequence by aligning the frequency
hopping sequence with the wideband transmission and adding a
frequency hopping indication in a second system information block,
wherein the frequency hopping sequence is leading to an out-of-band
deployment of said at least one system information block.
5. Method according to claim 1, wherein the wideband transmission
session comprises at least one of: a multimedia broadcast multicast
service, or a relay session for device-to-device operation with at
least one other wireless communication device.
6. Method according to claim 1, wherein the dedicated resource
region is operated according to at least one of: narrowband-IoT
modulation, or LTE category-M.
7. Method according to claim 1, further comprising broadcasting a
master information block, wherein at least one system information
block is transmitted in-band and at least one other system
information block is transmitted out-of-band, wherein the
deployment of the first system information block is determined by
the master information block.
8. Base node being part of a cellular wireless network configured
to operate with at least one wireless communication device, the
base node further being configured to transmit system information
in a frame structure, and to support a dedicated resource region
embedded in the frame structure for a subset of camping wireless
communication devices, wherein the dedicated resource region is
capable of being deployed at least in-band and out-of-band in
relation to a common frequency band, the base node comprising: a
collector for collecting a configuration parameter at least for
said dedicated resource region, configured to collect according to
a predetermined time period and to arrange said configuration
parameter in system information blocks, the base node further
configured to: identify if the dedicated resource region is
deployed in-band, add to at least one of said system information
blocks a valid subframe indication for submitting system
information blocks instead of wideband transmission blocks, in a
case where in-band deployment and wideband transmission session is
active, and transmit said system information blocks according to
said valid subframe indication, otherwise transmit said system
information blocks unchanged in a carrier frequency outside of the
common frequency band.
9. Base node according to claim 8, further configured to operate in
coverage enhancement scheme and to transmit the system information
according to said coverage enhancement scheme with a plurality of
repetitions, whereby the repetitions are transmitted in the
dedicated resource region in case of in-band deployment interrupted
through wideband transmission blocks and in each subframe
otherwise.
10. Base node according to claim 9, further configured to evaluate
if the wideband transmission session is active and if the system
information blocks are supposed to be transmitted according to
coverage enhancement scheme, and to deploy at least one system
information block out-of-band in case of the active wideband
transmission session.
11. Base node according to claim 10, further configured to transmit
at least one system information block repeatedly according to a
frequency hopping sequence by aligning the frequency hopping
sequence with the wideband transmission and adding a frequency
hopping indication in a second system information block, wherein
the frequency hopping sequence is leading to an out-of-band
deployment of said at least one system information block.
12. Base node according to claim 8, wherein the wideband
transmission session comprises at least one of: a multimedia
broadcast multicast service, or a relay session for
device-to-device operation with at least one other wireless
communication device.
13. Base node according to claim 8, wherein the dedicated resource
region is operated according to at least one of: narrowband-IoT
modulation, or LTE category-M.
14. Base node according to claim 8, configured to broadcast a
master information block, further configured to transmit at least
one system information block in-band and at least one other system
information block is transmitted out-of-band, wherein the
deployment of the first system information block is determined by
the master information block.
Description
FIELD OF THE INVENTION
The present invention relates to a method for transmitting system
information by a base node.
The invention also pertains to a base node using said method.
BACKGROUND OF THE INVENTION
The current evolvement of third generation long term evolution
(3GPP LTE) takes into account the increase of different types of
wireless communication devices. In particular besides cell phones
machine type communication (MTC) devices are getting more and more
widespread. Further such evolvements have to consider that many
MTC-devices have less computational power, which could even prevent
them to operate in the LTE networks over the complete addressed
bands.
For handling such low-cost devices it is therefore envisaged that
other resource region are embedded in the normal LTE resource
blocks, in particular supporting other modulation schemes. Known is
in particular the narrowband-IoT (NB-IoT) modulation, which is
dedicated for low-cost and low-bandwidth devices particularly used
for Internet of Things (IoT) applications, as well as LTE-category
0 or 1.
Further some of the MTC devices are operating in areas with bad
coverage, which cannot be fully mitigated by an increased
transmission power. This in particular affects metering devices or
vending machines. For solving this issue the concept of coverage
enhancement resp. enhanced coverage (EC) was developed. This
concept includes that by repeatedly transmission of signals an
accumulation of energy at the receiving device is carried out which
shall result in an increased link budget by e.g. up to 10 dB.
As part of the NB-IoT concept it is foreseen for such wireless
communication devices a special set of system information. This
special set is submitted in special system information blocks
(SIBs), dedicated for narrowband-IoT supporting devices, both in
normal and in enhanced coverage. Typically such SIBs are called
SIBx-NB, for distinguishing from common SIBs for common devices.
For simplicity reasons in the following these SIB for special
wireless communication device deployment especially intended for
NB-IoT are just called SIBs.
For accessing these SIBs in enhanced coverage they need to be
transmitted and correspondingly received in a repeated manner
leading to the coverage enhancement gain by combining each
repetition.
An issue occurs however when in the periodicity of the SIB
transmission the used resource is needed for other purposes. This
would harm the SIB transmission as a wrong transport block in the
averaging/accumulation process would ruin the whole
acquisition/decoding attempt.
This appears in particular, when in parallel in the used frequency
band a wideband communication session in the downlink, like
multimedia broadcasting to a common mobile handset, is carried out.
To acquire the system information all corresponding system
information blocks need to be received and combined repeated times
depending on their size and the coverage enhancement level needed.
It is possible to schedule one or even more than one SIB around
those subframes used for other purposes but not all of them without
having severe constraints in scheduling. In this case system
information blocks are not submitted in each subframe respectively
in each subframe intended according to their individual repetition,
but only in those where no multimedia broadcasting is
scheduled.
The receiving wireless communication devices are put in the
position to successfully include into the combining the relevant
subframes by additional datafields submitted in one of the system
information blocks. These additional datafields, the so-called
valid subframe indications, are supposed to indicate in which
subframe further SIBs can be expected and which subframes are not
to be considered for the accumulation for any of the SIBs because
of a wideband communication session, like MBMS or different
content.
This situation in particular affects NB-IoT SIBs, all the more when
transmitting in enhanced coverage. It is not only disadvantageous
as it takes longer and is more power consuming through the
subframes with no SIBs. Moreover the SIB1 carrying the valid
subframe indications is increased in size through such additional
datafields.
It is therefore the goal of present invention to overcome the
mentioned disadvantages and to propose a solution for an improved
system information block transmission for the dedicated resource
region.
Further alternative and advantageous solutions would, accordingly,
be desirable in the art.
SUMMARY OF THE INVENTION
For this it is according to a first aspect of the invention
suggested a method for transmitting system information by a base
node according to claim 1. It is further suggested according to a
second aspect of the invention a base node according to claim
8.
According to the first aspect of the invention it is proposed a
method for transmitting system information by a base node being
part of a cellular wireless network for long term evolution, to at
least one wireless communication device camping on the base node,
the base node being configured to support a dedicated resource
region for a subset of camping wireless communication devices,
which is capable of being deployed at least in-band and out-of-band
in relation to a common frequency band, the method comprising the
steps of: collecting configuration parameter for said dedicated
resource region according to a predetermined time period and to
arrange said configuration parameter in system information blocks,
identifying if the dedicated resource region is deployed in-band,
in case it is deployed in-band and a wideband transmission session
is active, adding to at least one of the system information blocks
an valid subframe indication for submitting system information
blocks instead of wideband transmission blocks, and transmitting
said system information blocks according to said valid subframe
indication, in case it is not deployed in-band transmitting the
system information blocks unchanged in a carrier frequency outside
of the common frequency band
The proposed method relates to base nodes of cellular wireless
networks supporting the technology standard of long term evolution
(LTE) networks, and further evolutions like LTE-M, LTE-Advanced
etc. Such base nodes are typically known as eNodeBs. Such cellular
wireless networks are preferably run by an operator in conjunction
with additional radio access networks (RAN), e.g. 2G, 3G, or beyond
4G. If the general architecture of the base node is maintained for
future generations, the inventive method is also applicable to such
technology standards.
As part of the evolvement of the LTE standard, eNodeBs are further
supposed to support dedicated resource regions. Such dedicated
resource regions are embedded in the LTE frame structure. Such
dedicated resource regions provide network resources for a special
type of wireless communication devices, in particular low-cost
resp. low-bandwidth devices, typically named as machine-type
communication devices (MTC). In these embedded resources even
different modulation schemes are possible, like narrowband-IoT,
LTE-CAT-M, even a GSM type of modulation.
The low-bandwidth devices do not have to have the capability to
process the whole range of 200 MHz in 1 ms, for operating in the
cellular wireless network, it is sufficient to only handle the
dedicated resource regions.
For such dedicated MTC devices also a special set of system
information block (SIB) is foreseen. SIBs are a collection of
relevant configuration parameter of the cellular wireless network
regularly and repeatedly broadcasted to the wireless communication
devices.
These SIBs are broadcasted within the dedicates resource region, in
particular a special channel, like PDCH.
There are different approaches to deploy the dedicated resource
region within the LTE band. As the LTE band is only occupied to 90%
with 15 kHz spaced subcarriers, there is at the borders remaining
an area called guardband, which can be used for dedicated resource
region.
For deployment of the dedicated resource region it is consequently
possible in-band deployment, that means amidst the LTE band frame
structure, with potentially colliding resource requirements.
Further out-of-band deployment is possible, which means the
dedicated resource region or parts/channels of it is positioned in
the guardband. Finally also standalone deployment, so unrelated to
a common LTE band, is possible. The deployment can affect the whole
dedicated region or only parts thereof, e.g. the SIBs, or only
parts of the SIBs. That is effectively a mixed deployment.
One of the potential resource collisions in the LTE band appears
when a wideband transmission session is active. This is in
particular the case for high-volume transmissions, like multimedia
broadcast multicast service (MBMS), or a sidelink operation for
device-2-device communication to a relay device connected to
further devices.
During wideband transmission sessions the whole allocatable band of
a subframe is completely allocated to the wideband transmission. In
that case no SIBs for the dedicated resources are scheduled.
In that case, the receiving wireless communication devices need to
be informed about the scheduling, in particular when SIBs can be
expected, and when this will not be the case. For that the first
system information block SIB1 has an additional data-field, which
is hereinafter called the valid subframe indication. With this
data-field the wireless communication device can figure out in
which subframes it can decode the various SIBs, and when this is
not the case.
Typically such valid subframe indication is implemented as a
bitfield resp. bit string where each bit indicates for which
subframes the SIBs are allowed resp. not allowed to be read. It is
expected that the size of the valid subframe indication might be
comparably large in the area of >1000 bits.
Consequently a problem appears with the size of the SIB1, and the
duration until all the SIBs, from SIB1 to SIB14 are successfully
decoded. During a wideband transmission session a wireless
communication device might need a remarkable amount of time until
the whole set of SIBs is decoded. This is disadvantageous as it
requires power, in particular for those wireless communication
devices running on battery.
Hence it is advantageous when the SIBs are deployed out-of-band or
stand-alone. Additionally the SIB1 is supposed to be kept as small
as possible, in particular the valid subframe indication is here in
the focus. Such indication would render no advantages, as in
out-of-band deployment no collisions with subframes used for
wideband transmission are available.
It is therefore suggested that before transmitting SIBs it is first
checked if the SIBs are deployed in-band or not. Only if the SIBs
are deployed in-band AND when a wideband transmission session is
active, then the SIB1 is enhanced with the valid subframe
indication and the SIBs are transmitted following the valid
subframe indication.
Should the deployment not be in-band, then the last step can be
omitted and the SIBs are continuously broadcasted--preferably in
the guardband--without the valid subframe indication.
In effect it is suggested that the valid subframe indication is an
optional field in SIB1, and only then used and populated when a
collision between SIB-NBs and/or wideband transmission subframe is
possible. In all other situation the SIB1 is shortened accordingly
and the wireless communication devices receiving the SIB1 only have
to decode the shorter SIB1 than when deployed in-band with
colliding wideband transmissions.
The advantage of the inventive method is a double effect: The
deployment in the guardband leads to faster transmission of the
SIBs and the SIB1 is diminished compared to an in-band-SIB1 with
full valid subframe indication. As the SIB1 is decoded most often
from all SIBs, this solution renders remarkable advantages for
wireless communication devices with limited battery resources.
Moreover the effect is tremendously increased when the base node is
operating with at least one camping wireless communication device
in enhanced coverage.
It is according to another preferred embodiment proposed a method
wherein the system information blocks are transmitted according to
a coverage enhancement scheme comprising a plurality of
repetitions, whereby the repetitions are transmitted in the
dedicated resource region in case of in-band deployment interrupted
through at least one of the wideband transmission blocks and
continuously otherwise.
According to this embodiment the repetitions of the SIBs until they
are sufficiently decoded by the receiving wireless communication
device needs to be coped with. It is therefore suggested that in
case of out-of-band deployment the SIBs are repeated without
interruption.
It is further suggested according to another preferred embodiment a
method further comprising the step of evaluating if the wideband
transmission session is active and if the system information blocks
are supposed to be transmitted according to an coverage enhancement
scheme, and deploying at least one system information block
out-of-band in case of the active wideband transmission
session.
With that embodiment the base node gets aware of the situation that
wireless communication devices operating in enhanced coverage are
currently camping on the base node. Should then a wideband
transmission session become active, then the base node takes
measures to safely supply the low-bandwidth wireless communication
devices operating with the dedicated resource region at least with
the system information.
Hence it takes the decision that at least parts of the system
information blocks are shifted to out-of-band deployment, if
available. This might not affect all SIBs, but nonetheless the time
until all SIBs are decoded, in particular having in mind the
repetitions for enhanced coverage, is immensely reduced.
This is in particular advantageous as it minimized the risk that a
wireless communication device operating in enhanced coverage might
not manage to read the whole set of SIBs during one BCCH
modification period. Should this not be manageable, the reading
would start again and much more power is drained.
It is further suggested for such a situation another embodiment
comprising the step of transmitting at least one system information
block repeatedly according to a frequency hopping sequence by
aligning the frequency hopping sequence with the wideband
transmission and adding frequency hopping indication in a second
system information block, wherein the frequency hopping sequence is
leading to an out-of-band deployment of said at least one system
information block.
Here effectively a frequency hopping scheme is suggested. With that
the base node is in the position that the same SIB which is
repeated for enhanced coverage a couple of time, moves in the
frequency range, in particular is deployed once in-band and once
out-of-band.
Further the suggested alignment of frequency hopping sequence with
the wideband transmission scheme is dedicated to avoid wideband
transmission subframes for the scheduled SIBs, that is the SIBs are
for repetition then moved into the guardband.
For safe reception the SIBs get additionally an indication about
the frequency hopping, that is the frequency resp. subcarrier,
where the next repetition of the SIB can be decoded. That is needed
for the receiving wireless communication device in order to figure
out which frame to decode in order to receive the next repetition
of the SIB.
This approach is in particular flexible as it allows situative
shifting of the SIBs depending upon the traffic in the LTE band.
Having in mind that the low-cost devices have a low priority for
the cellular wireless network, it can be assumed that resources for
these devices will be shifted where something is available.
Therefore this approach leads to a better flexibility and
robustness of broadcasting.
According to another preferred embodiment it is proposed a method
wherein at least one system information block is transmitted
in-band and at least one other system information block is
transmitted out-of-band, wherein the position of the first system
information block is determined by the master information
block.
This embodiment indicates a mixed deployment of the system
information blocks. The base node is put in the position to
distribute the SIBs in-band or out-of-band, in particular taking
into account if wideband transmissions are available.
According to a second aspect of the invention it is proposed a base
node being part of a cellular wireless network for long term
evolution configured to operate with at least one wireless
communication device, the base node further being configured to
support a dedicated resource region for a subset of camping
wireless communication devices, which is capable of being deployed
at least in-band and out-of-band in relation to a common frequency
band, the base node comprising: a collector for collecting
configuration parameter at least for said dedicated resource
region, configured to collect according to a predetermined time
period and to arrange said configuration parameter in system
information blocks, a deployment identificator, configured to
identify if the dedicated resource region is deployed in-band, the
base node further configured to add to at least one of said system
information blocks an valid subframe indication for submitting
system information blocks instead of wideband transmission blocks,
in case the deployment identificator indicates in-band deployment
and wideband transmission session is active, and transmit said
system information blocks according to said valid subframe
indication, otherwise transmit said system information blocks
unchanged in a carrier frequency outside of the common frequency
band.
The second aspect shows the same advantages as the first
aspect.
As it is shown this invention advantageously solves the depicted
problems and proposes a solution which smoothly works with the
current technology standard evolvement.
BRIEF DESCRIPTION OF THE DRAWINGS
The following description and the annexed drawings set forth in
detail certain illustrative aspects and are indicative of but a few
of the various ways in which the principles of the embodiments may
be employed. Characteristics and advantages of the present
invention will appear when reading the following description and
annexed drawings of advantageous embodiments given as illustrative
but not restrictive examples.
FIG. 1 represents the frame structure over an LTE frequency band of
a base node according to the exemplifying embodiment;
FIG. 2 shows a first flow chart setting out an exemplifying
embodiment of the inventive method;
FIG. 3 represents in a second flow chart another exemplifying
embodiment of the inventive method.
FIG. 1 schematically shows the downlink frame structure 1 of a base
node according to an exemplifying embodiment of the invention for a
base node supporting long term evolution (LTE). Such a base node is
commonly known as an eNodeB and is part of a cellular wireless
network at least supporting the 3GPP LTE technology standard. On
each base node a plurality of wireless communication devices are
supposed to camp.
The base node is in particular configured to support besides the
common full LTE band also a dedicated resource region of the frame
structure. Such a dedicated resource region is preferably
designated for low-bandwidth wireless communication device which
are not capable of decoding the whole range of a frequency band.
Moreover the dedicated resource region may even be provide a
different modulation scheme as the rest of the band. This in
particular relates to narrowband (NB)-IoT modulation scheme.
Said frame structure 1 comprises the normal LTE band 3, e.g. of 18
MHz occupied by 1200 subcarriers spaced 15 kHz in the entire 20 MHz
LTE band 1. This is the frequency band that is used and decoded by
the common cellular handsets, and is divided in a predetermined
amount of subcarriers, each spanning over 15 kHz.
Additionally the normal LTE band 3 is bordered by one guardband 4
on each ends of the frequency band. That guardband covers a range
of up to 1 MHz on each side in case of 20 MHz LTE band. In general
LTE only occupies 90% of the nominal bandwidth. It is currently
foreseen that the guardbands 4 could be used as a dedicated
resource region in particular for NB-IoT, but this is not
mandatorily the case.
At the center of the LTE band 3 it is situated the master
information block 10. This includes in particular scheduling
information, including the positioning of the first system
information block SIB1 8. This SIB1 8 is dedicated for a certain
subset of camping wireless communication devices, in particular
those operating in NB-IoT. Further another SIB1 (not shown) is
available for common mobile handsets. The SIB1 is typically
scheduled following a general pattern, e.g. every even system frame
number (SFN), like here shown all two subframes.
The SIB1 8 is mainly positioned at a fixed frequency. Here it is
shown a fixed frequency inside the LTE band 2, which means the SIB1
is deployed in-band. Further other SIBs are deployed, like SIB2 9
and further SIBx 5.
The SIBx are deployed in the guardbands 4, this deployment is
called out-of-band. Such mixed deployments are possible, but not
the only way of operation. In particular the guardband may also be
used for dedicated data transmissions.
In the vertical direction of the schematic illustration the
subframes are displayed. Here 6 subframes are shown, each covering
a duration of 1 ms. In the LTE band 2 there are indicated by
different hatching two wideband transmission subframes 7. These
subframes are reserved for wideband transmission sessions like
MBMS. In particular during wideband transmission subframes 7 no
SIBs are scheduled.
Hence it is necessary at least in SIB1 8 to indicate that the
respective wideband transmission subframes 7 are not to be decoded
by the receiving wireless communication devices when they want to
read the SIBs. In particular SIB1 8 is not scheduled in general
during the wideband transmission subframes.
For the decoding of other SIBs 9 SIB1 contains a valid subframes
indication i.e. indicating the subframes containing wideband
transmission instead of NB-IoT transmission in-band, where
according to the scheduling pattern of SIB 9 it would have been
scheduled, but is not omitted (9a). In this case a pattern for the
SIB 9 of all 4 subframes is foreseen, but in the valid subframe
indication for the fifth shown subframe there is a notion that SIB
9 will be omitted here.
In particular in conjunction with enhanced coverage if would
endanger the reception of the SIBs, if the wireless communication
device would continue to accumulate the wideband transmission
subframes to the received SIB transmissions of other subframes. If
subframes with a different content would be included in the EC
combining process the accumulation would not converge to
decoding.
Further it can be seen the SIB1 is repeated more often as others.
This is the system information block with the most important
information, like the system value tag, access barring indications
etc. Consequently it is the SIB1 which is read most frequently by
the receiving wireless communication devices
On the other hand due to this situation each increase of the size
of SIB1 8 would increase the power needed for decoding the SIB1
remarkably. This effect is even immensely increased in case of
enhanced coverage through the needed repetitions until it can be
successfully decoded once, effectively it takes much longer to
decode it.
With the omission of SIB1 transmission during wideband transmission
subframes this decoding time would even be enlarged.
The situation is different for SIBs 5 scheduled in the guardband 4.
Here it is possible irrespective of wideband transmissions to
decode SIBs in each subframe, that is continuously.
Hence, for these SIBs the SIB1 does not have to comprise any
indication in terms of at which subframes the decoding needs to be
suspended.
Moreover if even the SIB1 and all further SIBs would be positioned
in the guardband 4, then such additional indication data field of
SIB1 could be omitted completely.
This indication is therefore according to this embodiment of the
invention optional and can be omitted in case that some or even all
SIBs are deployed out-of-band.
In effect this type of scheduling would, in particular for wireless
communication devices operating in enhanced coverage, reduce the
duration and the efforts for the wireless communication device for
receiving a complete set of SIBs dedicated for this type of
wireless communication device. This leads in particular to a
quicker decoding with lower power consumption.
FIG. 2 shows an exemplifying flow chart of a preferred embodiment
of the inventive method. It starts in step S1 with the base node
(BS) of a LTE network, and this base node is configured to support
NB-IoT, respectively any other dedicated resource which can be
positioned in the guardband.
In step S2 the base node then determines if the NB-IoT resource
blocks are deployed in-band or out-of-band. This in particular
related to the SIB broadcast, e.g. as part of the PBCH, but could
also affect other, also dedicated, channels. In this simplifying
embodiment it is assumed that the situation is considered that
either all or none of the SIBs are deployed out-of-band or not. In
reality also a mixed approach is possible, and would require an
amended approach.
In decision step S3 it is now branched in dependency of the
deployment to an in-band handling or otherwise. Besides out-of-band
deployment also stand-alone deployment would be another option.
This would be a deployment of the NB-IoT unrelated to a common LTE
band. Nevertheless the same method steps apply to a determined
out-of-band and standalone deployment.
Should the determination result in an out-of-band or standalone
deployment then the method flow branches to step S5 and allows
transmitting the SIBs continuously. That means the SIB transmission
is not affected by possible wideband transmissions.
In case of in-band deployment the method flow branches from step S3
to decision step S4. Here it is now checked if a wideband
transmission is detected. Such a wideband transmission relates in
particular to a session of the multimedia broadcast multicast
service (MBMS). Should this not be the case, then the process flow
branches again to step S5, where the SIBs are transmitted
continuously, that is not interrupted, but in this case in in-band
deployment.
Otherwise it is branched to step S6, where the SIB1 is enhanced by
a valid subframe indication. This valid subframe indication
indicates to the receiving wireless communication devices which
subframes may be read for decoding the SIBs, and which are not, due
to wideband transmission subframes. Such valid subframe indication
is not needed for the case of out-of-band deployment and as long as
no wideband transmission session is active.
Consequently the SIB transmission follows in step S7 this rule and
hence the set of SIBs, including the enhanced SIB1 is transmitted
in-band, but not during wideband transmission subframes.
The receiving wireless communication devices obviously have in the
case of continuous SIB transmission faster and with less decoding
efforts decoded the complete set of SIBs than with the interrupted
transmission. This hold true all the more when the wireless
communication devices are operating in enhanced coverage.
FIG. 3 shows another preferred exemplifying embodiment of the
inventive method. Here it starts in step S10 with a base node
supporting NB-IoT, but this is already deployed in-band. It is
checked in decision step S11, if an operation in enhanced coverage
is carried out.
This needs to be supported by the base node as well, in terms of
repetition of the transmitted data. The density and number of
repetitions of the SIBs depends on the level of coverage
enhancement that is intended to be supported by the eNodeB. I.e. a
SIB needs to be received sufficiently often prior its content could
change in a new BCCH modification period. The base node can support
the so-called CEmodeA, that means no or only shallow fading which
requires only little accumulation over a few repetition. Opposed to
that is CEmodeB which is deep coverage enhancement. For CEmodeA it
should be possible to acquire information by very little
accumulation and hence SIBs can be scheduled at a lower density and
hence being scheduled contention free around wideband transmission.
Should the base node not operate in enhanced coverage or only in
CEmodeA the process flow branches to step S12, which complements
practically to a branch to step S4 of FIG. 2.
In case of deep enhanced coverage resp. CEmodeB it is branched to
decision step S13, where it is checked if a wideband transmission
session is active or not. If no wideband transmission session is
active then in step S14 SIBs are consequently transmitted
continuously in-band.
Otherwise it is branched to step S15. Here it is decided by the
base node to deploy a subset, that means at least one of the SIBs
out-of-band. Typically it is not the SIB1 which can be moved to the
guardband, as it is expected to stay on a constant frequency. But
the SIB1 indicates to the receiving wireless communication devices
where from now on the other SIBs SIB2-SIB13 are deployed.
Consequently the deployment then takes effect resulting in method
step S16, wherein the in-band-SIBs, in particular SIB1, are
scheduled not overlapping with wideband transmissions, while the
out-of-band-SIBs are transmitted in the guardband with the
possibility to be scheduled at all times. Only for the in-band-SIBs
overlapping with wideband transmission the SIB1 needs to indicate
with the valid subframe indication in which subframes intended SIB
transmission would resp. would not collide with wideband
frames.
The presence of wideband transmission frames during other times
would not need to be indicated, hence if the number of potential
collisions is sufficiently small this could be made by direct
indication of the subframe and its repetition instead of indicating
the validity of each subframe within a modification period.
In the above detailed description, reference is made to the
accompanying drawings that show, by way of illustration, specific
embodiments in which the invention may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the invention. It is to be
understood that the various embodiments of the invention, although
different, are not necessarily mutually exclusive. For example, a
particular feature, structure, or characteristic described herein
in connection with one embodiment may be implemented within other
embodiments.
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